The present invention relates to concentrated heavy duty liquid detergent compositions. Such compositions contain, as the active detersive ingredients, a nonionic surfactant component, an anionic surfactant component, and an alkanolamine component. The compositions also contain a minor proportion of a fatty acid corrosion inhibitor, and, in a preferred embodiment, an alkali metal base.
Heavy duty liquid detergent compositions are well known in the art. Usually such compositions (see, for example, U.S. Pat. Nos. 2,908,651; 2,920,045; 3,272,753; 3,393,154; and Belgian Pats. 613,165 and 665,532) contain a synthetic organic detergent component which is generally anionic, nonionic, or mixed anionic-nonionic in nature; an inorganic builder salt; and a solvent, usually water and/or alcohol. These compositions frequently contain a hydrotrope or solubilizing agent to permit the addition of sufficient quantities of surfactant and builder salt to provide a reasonable volume usage/performance ratio. While such liquid detergent compositions have been found effective for some types of home laundering, the presence of inorganic builder salts in such compositions may be undesirable from an ecological standpoint in improperly treated sewage.
Several attempts have been made to formulate builder-free, hydrotrope-free liquid detergent compositions. For example, U.S. Pat. No. 3,528,925 discloses substantially anhydrous liquid detergent compositions which consist of an alkyl aryl sulfonic acid, a nonionic surface active agent and an alkanolamine component. U.S. Pat. No. 2,875,153 discloses liquid detergent compositions containing a nonionic surfactant component and a sodium soap component. U.S. Pat. No. 2,543,744 discloses a low-foaming dishwashing composition comprising a nonionic, water-soluble, synthetic detergent and a water-soluble soap in the form of an alkali metal, ammonium or amine salt. All of these detergent compositions are effective for certain types of washing operations, but none of the commercially available compositions of this kind are highly effective both as pre-treatment and heavy duty washing agents for cleaning both natural and synthetic fabrics.
U.S. Pat. No. 3,663,455 relates to liquid cleaning and defatting compositions containing a nonionic surfactant, an alkanolamine-neutralized anionic surfactant, alkanolamine, and fatty acid.
The co-pending application of Collins, Ser. No. 222,363, filed Jan. 31, 1972, entitled LIQUID DETERGENT COMPOSITIONS, relates to detergent mixtures comprising a high ratio of nonionic to anionic surfactant and free alkanolamine.
U.S. Pat. Nos. 3,709,838; 3,697,451; 3,554,916; 3,239,468; 2,947,702; 2,551,634; British Pat. Nos. 900,000; 842,813; 759,877; Canadian Pat. No. 615,583; and Defensive Publications T903,009 and T903,010 disclose a variety of detergent compositions containing mixed nonionic-anionic surfactants, both with and without alkanolamines.
As can be seen from the foregoing, a substantial effort has been expended in developing low-built and builder-free detergent compositions in liquid form. Yet, there are several problems associated with the art-disclosed compositions which render them less than optimal for widescale use.
First, many of the prior art compositions contain phosphorus-based builder materials. Such builders, and compositions containing same, may not be useful in areas of the country having improperly treated sewerage effluents.
Second, many of the prior art compositions are formulated at too low a ratio of nonionic:anionic surfactant to provide optimal oily soil removal from fabrics.
Third, many of the prior art compositions are formulated to provide satisfactory through-the-wash fabric cleaning performance, but do not provide optimal pre-wash treatment of oily soil found in collars and cuffs of fabrics. Most users of liquid laundry detergent compositions expect that superior fabric cleansing can be secured by applying the liquid product directly, at full strength, to heavily soiled areas of the fabric prior to laundering. Accordingly, it is desirable to provide a liquid detergent having optimal pre-treatment cleaning benefits as well as optimal through-the-wash cleaning performance.
Finally, the prior art (see U.S. Pat. No. 3,663,445) discloses that surfactant compositions containing high concentrations of ethylene oxide-based nonionic surfactants and alkanolamines must contain at least about 3% by weight of fatty acid salts to provide the desired product stability and/or performance characteristics. Due to supply problems with fatty acids, it is highly desirable to provide stable, high cleaning, mixed nonionic/anionic detergent compositions having a high concentration of ethylene oxide-based nonionic surfactants without the need for such large amounts of additives derived from fatty acids.
The co-pending application of Collins, et al., entitled LIQUID DETERGENT COMPOSITIONS, Ser. No. 376,641, filed July 5, 1973, the disclosures of which are incorporated herein by reference, teaches that certain ethylene oxide-based nonionic surfactants can be used at high concentrations in liquid detergent compositions, in combination with alkanolamines and certain anionic surfactants, and without the need for fatty acid-based stabilizers. The compositions disclosed by Collins, et al., provide builder-free, liquid detergent compositions which exhibit both excellent pre-wash and through-the-wash fabric cleansing. It would be desirable to include a corrosion inhibitor in such compositions. Unfortunately, many such inhibitors are phosphorus-based and are obviously not the compounds of choice when formulating phosphorus-free compositions. Moreover, any corrosion inhibitor must be compatible with the essential cleaning agents in the formulation, as well as being safe for use on fabrics.
It has now been discovered that fatty acids especially oleic acid, used in minor proportions in the present compositions provide good corrosion protection in automatic washers. Inclusion of a sufficient amount of an alkali metal base also in the present compositions provides even better corrosion protection.
It is an object of this invention to provide stable liquid detergent compositions which exhibit excellent pre-wash and through-the-wash fabric cleaning, yet which protect metal surfaces from corrosion.
It is another object herein to provide stable liquid detergent compositions containing high concentrations of nonionic surfactants and free alkanolamines, anionic surfactants, and minor amounts of fatty acid corrosion inhibitors, said compositions being formulated to exhibit optimal cleaning and sudsing characteristics.
These and other objects are obtained herein, as will be seen from the following disclosure.